Yes, you can use Bixmile and RaceQs side by side.
Why would you do this?
When your regatta is using RaceQs for regatta replays, but you want to use Bixmile functions like reviewing Grib files and connect to on board instruments via Wifi, NMEA2000, Apple Watch connectivity etc.
How would you do this?
Use the Bixmile app, before and during your trip. Upload your data to Bixmile.com. Export your data from Bixmile.com. Import your data in RaceQs.